This invention relates to disposable syringes and needle containing appliances for use in injecting or withdrawing fluids. They are adapted to prevent accidental needle-stick injury by encapsulation of needles for proper disposal after use is complete. The term syringe denotes an instrument used for injecting or aspirating fluids.
In the health care field, health care workers such as nurses and other professionals, as well as related personnel such as house keeping staff and the like, are subject to "stick-needle" injury. A needle-stick occurs whenever a needle passes through the skin of a person by intension or by accident. Disposable medical devices are often used which contain needles for subcutaneous injection, for gaining access to a person's blood vasculature for therapeutic administration of a blood product or medication delivery, or for obtaining a sampling of blood from a patient for analysis. Current devices being utilized provide incentives for health care workers to either recap or clip or otherwise protect needles after use of the device is complete. It is often after use is complete and prior to disposal that workers are most at risk from accidental and self-inflicted needle-stick injury. Even if needles are carefully discarded without being protected and the primary health care provided escapes injury, the cleaning staff or other innocent bystanders are very often still at risk. Before needles can be incinerated or properly buried in a landfill, human contact is possible and occurs frequently. Needles are contaminated once used with nosocomial germs such as the hepatitis or AIDS virus. Each and every used needle poses a potential threat of transferring dangerous microorganisms both inside the hospital and in the community. Availability of operable used disposable needle containing devices is a contributing cause of repeat drug abuse where syringes are shared and also a key factor in disease transmission. A needle-stick injury, when reported, is usually followed by a shot of passive immunizing agent to reduce the chance of contracting hepatitis or tetanus infection. There is no known immunoglobulin or anti-serum for the treatment of the HIV AIDS ARC retroviruses. Therefore, prevention of needle-stick injury has become of paramount importance. Blood donors or potential AIDS patients are entitled to their privacy and even if tested, may test negatively for AIDS or other diseases during the incipient stages. Such persons receiving a needle-stick may engage in subsequent behavior which would unknowingly transmit the virus--even in doing something as harmless and seemingly altruistic as making a blood donation. Precautionary measures when taken, result in discomfort and apprehension by the recipient as well as added cost to the responsible health care facility. Unfortunately, needle-stick injury is a "no win" situation and will likely take on added importance as times passes. Knives and swords are housed in protective scabbards when not in use. Just as guns are required to be holstered and permits obtained in their responsible use, a needle may begin to take on the same or similar lethal significance. This strengthens the argument for cost effective sealed encapsulation after use is complete.
Numerous modified disposable needle containing appliances such as syringes, catheters and dental or medical hypodermic syringes have been discovered in recent years to lessen the likelihood of needle-stick injury. Alternative disposable needle holders, syringes or other appliances may be rendered inoperable after use to combat drug abuse and disease transmission.
Janine Jagger, MpH, PhD, an assistant professor of Neuro-surgery from the University of Virginia Medical Center, gave testimony in Washington D. C. before the Department of Labor, Occupational Safety and Health Administration (OSHA) board to consider guidelines and rules on occupational exposure to bloodborne pathogens on Sep. 12. 1989. Dr. Jagger authored a study published in the New England Journal of Medicine, August 1988 issue, and disclosed a table listing six major devices causing needle-stick injuries as well as way in which the injuries occurred. Dr. Jagger has learned how to make projections of potential reductions in needle-stick injury following specific design modifications. Devices listed included:
(1) Disposable syringes, being responsible for 1/3 of all needle-stick injuries and 1/2 of those injuries from attempts to recap used needles.
(2) Prefilled cartridge syringes where injury was related to disassembly or improper disposal of needles.
(3) Winged intravenous catheters with tubing for fluid infusion or blood sampling where workers receive a stick when disposing of the winged needles and tubing.
(4) The catheter placement unit used to gain access to the vascular system wherein the catheter is inserted into a vessel and the rigid stylet or needle removed and disposed of quickly so that the unprotected needle poses a hazard to housekeeping staff as well as other workers and patients.
(5) The vacuum tube holder which is most often used for drawing blood, and the phlebotomy needle must be wrenched from the reusable holder after use. Health care workers often recap these needles to save time in disposal and to guard against needle-stick injury prior to disposal.
Inadvertent detachment of intravenous lines and subsequent dangling tubing with needles attached have been a problem in past years. Surgical tape has been a make shift solution to secure the connections. This denotes poor product design as well as inattention to the needle-stick hazard and has resulted in may needle-stick injuries. Methods to shroud or otherwise sheath the needles to protect them have been obvious solutions. In some cases, needles have been eliminated altogether from such tubing and systems. Dr. Jagger found that rates of needle-stick injury were highest for devices requiring disassembly after use. These are the last five devices as mentioned above and injury can be attributed to a lack of protection for the worker's hands during disassembly.
Product structure improvements will solve the needle-stick injury problem. Optimal solutions will eliminate needles from designs where possible or minimize their use. Otherwise, needles should always remain covered by a shroud or encapsulation means or ferrule or barrel with an open end for receiving whatever needs to have contact with the point of a needle ie. injection cap or medication vial membrane. Membranes must be penetrated in non-coring fashion. Unless the industry gravitates to standard packaging, such approaches would not always be practical. Because of the large variety of uses and requirements for needles, other means must be found to protect exposed needles. Jagger believes that best designs should be incorporated into a device instead of being provided as a separate accessory. A device should provide protection prior to disassembly and should remain in effect after disposal to protect the waste handler, as well as others who may encounter the device. Such safety designs should be simple to use and require little training to use effectively. Any incentive to make further use of a used device should be removed. A disposable device should be irreversible. Any change should not increase manufacturing cost of difficulty in use. Device disposal should automatically comply with OSHA recommendations. These include that needles should not be recapped, purposely bent or broken by hand, removed from disposable syringes or otherwise manipulated by hand. After they are used, disposable syringes and needle should be placed in puncture resistant containers. Such containers shall be constructed so that they will not spill their contents if knocked over and will not themselves allow injuries when handled. It is important that such containers by located on patient floors or any other setting where blood is drawn and needles are handled. Prior art devices that appear to be inconsistent with recommendations include U.S. Pat. Nos. 4,695,274 to Fox; 4,610,667 to Pedicano; 4,596,562 to Venon; and 4,573,976 and 4,425,120 to Sampson.
In particular, devices that protect a needle after use is complete may be divided into two categories. First, there are devices that assist the user in resheathing or recapping the needle after use. These provide for replacing a detachable cap or sheath without the user's hands coming into proximity to the needle point or otherwise contain a movable ferrule or cylinder which may be moved axially along the syringe and relocated around the needle to cover and protect the point. The second category of devices developed to protect needles incorporates various mechanisms for retracting the needle into the syringe barrel or into a protective case. U.S. Pat. Nos. 4,676,783 and 4,781,692 to Janine C. Jagger illustrate winged retractable safety needles. It is pointed out that winged safety needles are currently recapped using the same cover that is provided in the packaged product. Such products encourage hand movement toward needle points and thus, needle-stick injury. Jagger points to protection for winged needles or catheters by providing a rigid housing proximal to the wings into which the needle may be withdrawn after use is complete. This occurs when the user pulls on the hub end and tubing or tabs thereof to retract the needle into the protective housing. It is not clear how well the needle is anchored in both the exposed and retracted position. Although the needle may be protected in this manner, it is possible that such needles may become inadvertently exposed during or after disposal because a lock of the retracted needle is not provided. If applied to catheter placement unit use, such a concept should also provide a viewing means of blood flashback. Such a device must be irreversible. The instant invention provides for such shortcomings in a cost effective manner.
Devices that assist the user in recapping or resheathing the needle do not go far enough to render the device inoperable. Recap devices that cannot make use of standard parts may be lost and slide sheaths often inadvertently retract to leave the unprotected needles of such devices exposed. Besides the extra expense for additional parts an time lost in cumbersome manipulation, such devices are inconvenient and expensive. Devices in this category include U.S. Pat. Nos. 4,610,667 to Pedicano; 4,596,562 to Vennon; and 4,573,976 and 4,425,120 to Sampson and 4,795,443 to Peach.
Prior retractable needle devices have shortcomings. Some devices require partial assembly such as U.S. Pat. Nos. 4,710,170 to Haber and 4,592,744 to Jagger. This is potentially confusing, and disassembled parts may become contaminated and unprotected. A primary shortcoming of most retractable needle syringes is that each requires use of non-standard needle support structures ie. a needle and base that must be specifically manufactured as opposed to using standard parts known to the medical industry. This results in a lack of interchangeability with available needle configurations and added cost, besides lack of familiarity and less acceptance by end users. Devices in this category include U.S. Pat. Nos. 4,507,117 and B1 4,507,117 to Vining et. al., 4,675,005 to DeLuccia and 4,747,830 to Gloyer. The reissued Vining patent provides means for repetitively and selectively locking and unlocking the needle to the plunger piston during use. Requiring the needle base to be locked into the plunger could add additional unnecessary burdens which may hinder ease of operation as well as teaching the correct use of the syringe. Locking the needle portion to the barrel portion is a worthy pursuit but should emphasize the use of standard parts and commercially available needles.
This inventor has provided the dual capability of use as a conventional syringe with a front mounting luer-lock fitting, should a user have a special need for such mounting. The term luer denotes the attachment of a needle to a syringe tip and is coined in honor of the nineteenth century German instrument maker. A glass syringe with airtight glass piston is called a Luer syringe. Luer-lock is a term used to denote the attachment of the female receiving cavity of a standard truncated conical hypodermic needle with ovate flange to the corresponding male fitment and threaded collar of a syringe barrel. If a threaded collar is not present, the syringe is then said to have a luer-slip tip. The instant invention also provides an internal luer-lock inside the syringe tip. In this case, the male fitment is formed on the tip of the plunger piston and a seal is formed along the outside smooth portion of the standard needle when it is mounted and integrated into the syringe tip.
Several methods of forming industrial seal are well known to the automotive, aerospace or pipe fitting industry. Several well accepted joint fittings include:
(1) Threaded taper seal
(2) Gasket or crush plate seal
(3) O-ring seal.
Redundancy or combinations of the above are often provided when a reliable seal between joints is of critical importance. However, redundancy in itself is often a sing of poor understanding of stress factors that play upon the joint. For example, aerospace engineers utilize redundant O-rings in joints of booster rockets. The theory is that should the first O-ring be degraded and fail causing escape of hot gases and head, the back up O-ring provides a safety cushion to prevent a catastrophy. This approach may indeed provide appropriate protection but can never be totally reliable. This is because redundant O-rings, in themselves, are not configured to meet the challenge borne by tremendous internal pressures that develop during launch. Environmental factors such as low temperatures can compound problems and perturb inadequacies in unreliable seals. A reliable approach should take advantage and reflect appreciation of the large mass of each booster section and apply that mass directly to the joint and O-ring or rings. Therefore, a taper fit combined with one or more O-rings would provide the reliability and quality assurance that has been lacking in the past in this critical area of the space technology field.
A sealing means is also of critical importance between a needle and syringe. An externally mounted needle is adequately sealed in a luer-slip or luer-lock tip syringe in most instances. In normal use, pressure within the syringe does not build up extraordinarily. However, should a syringe piston be quickly depressed, a needle mayfly off the tip like a missle. An internally mounted needle is urged to become integrated with the syringe tip. A proper seal is of critical importance. A standard needle has a smooth tapered truncated conical hub or base section near an ovate flange. A matching taper or plastic O-ring integrated distal to luer-lock threads will allow a superb seal using a standard needle and can be provided at no additional cost to the manufacturer. Mechanical function requires that any seal between joints be equal to or superior to the wall strength between joints, under all working conditions and in all environments where a task is performed. By mounting a needle within a syringe barrel tip so that the needle base becomes integrated with the barrel tip, a superior seal which in and of itself, advances knowledge in the field, is thereby acquired.
By providing an outside luer, a second needle may shield a primary needle inside or a second catheter sheath could be passed off the tip as the needle is retracted inside the barrel. The term hypodermic syringe denotes a small syringe armed with a hollow needle for use in giving remedies by the subcutaneous method.
It is desirable to be able to both retract a needle into the syringe barrel and thereafter make the syringe unreusable. In addition, it is desirable that, when a plunger of the syringe is completely depressed, the grommet making up or surrounding the needle mounting hub is compressed which results in very little or no air remaining in the interior of the syringe and when the plunger piston is released, will spring back or rebound from the needle mounted internally in the barrel collar to facilitate self-aspiration of fluid while providing easy release from the needle base. This helps to insure that air can be vented from the barrel and replaced with liquid.
A device of this type is useful not only as a syringe for delivering or withdrawing fluids from a patient, but is also used in conjunction with a modified syringe barrel known as a needle holder-dropper device for the purpose of drawing blood. Arterial or venous catheter placement capability has been noted. A spinal tap apparatus, dental syringe or any similar device having a needle may be provided in order to protect the health care provider from needle-stick injury during or after use. The term dental syringe is used to denote a breach-loading metal cartridge syringe into which fits a hermetically sealed glass cartridge containing an anesthetic solution. The sealed glass cartridge consists of a glass barrel with a plunger grommet at one end and a sheet metal cap which is open and covers a rubber disk and is crimped over the opposite end. The glass cartridge may form the packaging for providing a syringe upon addition of a plunger piston and cap-needle mounting means.
A needle containing device is most dangerous at the time a task is being performed with it. Caps are prone to be lost or fall off and exposed needles then become a hazard to handlers and bystanders alike. Even a retractable syringe, if filled with blood or other fluid, has an exposed and potentially dangerous needle. U.S. Pat. No. 4,795,443 issued Jan. 3, 1989 is for a stick protector that clips onto a syringe barrel and can be guided over an exposed needle. However, such a device could be made even simpler and less expensive if the stick used rings to attach to the syringe barrel and standard cap that is provided along with a standard needle.
Glass ampules are widely used in the delivery of medicine. A glass top has a constriction point which is broken to allow access to the liquid or powder inside the ampule. Such delivery is associated with the possibility that shards or splinters of glass which may fall into the vial during breakage of the top may subsequently be aspirated unknowingly with the medicament. Vented needles have been developed to prevent coring of rubber should a vial have a rubber stopper that is penetrated by a needle. Such needles are expensive. Elaborate filter means such as straws have been developed to address the glass splintering problem. All alternatives are expensive and inconvenient. Therefore, a cost effective method of converting a cartridge ampule or other glass containment means into a syringe and keep the medicament separate from the needle until the time of use would be desirable if cost effective and provided the needle penetrate any rubber seal or disk in non-coring fashion. A machined light socket ferrule of appropriate configuration can be integrated into the tip of a glass syringe barrel and a male fitment included on a glass plunger piston to provide a retractable glass syringe with internal bayonette attachment for a retractable needle base.
This invention relates generally to disposable hypodermic syringes and more particularly to pre-loaded devices of this type employing a special pre-mounted needle adapted to pierce a sealing membrane or the syringe body of a syringe glass containment means, thereby rendering the syringe or cartridge operable. The sealing membrane is pierced so that coring of the membrane is avoided.
U.S. Pat. No. 3,825,003 to Kruck teaches precise and accurate control of the needle movement, especially with respect to penetration of the seal of a syringe body or cartridge. In this needle and cap assembly, the non contaminating cover is easily and quickly removed wherein a double pointed needle pierces the membrane. A needle lock is constituted of ears on the needle and cooperably locking shoulders on a sealing type cover. The cover, by means of its shoulders, holds captive a needle hub so as to releasably hold the needle in its advanced position against spring action. Upon turning the cover slightly, the shoulders thereof disengage the ears of the needle hub and the needle snaps to its retracted position so as to pierce the membrane to enable discharge of the product to be effected. Such a needle requires special tooling and equipment to incorporate a biasing spring in its structure. The number of parts required to make the hub of the needle rather large and, thus, impractical for use with a small syringe barrel or cartridge cap. In British Patent Specification number 1,489,813 and U.S. Pat. No. 3,974,832 to Kruck are found the teaching that in prior devices, where the hub and needle were free to turn as the latter pierced a sealing membrane, there was the danger that small pieces of membrane would tear off as the needle point axially rotated during passage. These pieces, if drawn into the hollow needle and injected into a patient, would have serious consequences. If screw threads were used, they must be "started properly" to prevent binding or damage and malfunction. According to the present invention, there is provided a needle and special coaxial mounting cap-needle assembly for a hypodermic syringe which provides a manual method of mounting a needle which, by eliminating the spring, makes the overall structure more affordable. The structure includes a needle having at least a point at one end for piercing the pierceable membrane of a syringe and a key, threaded member or a fastener made up of a hub intermediate the needle ends and having as a keying portion a standard needle base with a threaded portion or fastening means to adapt to a round or alternate eye opening cap of a syringe cartridge; or a modified eye cap with a mateable key opening corresponding in size and shape to the flange or shoulders of the needle assembly support base. In each case, it is important that the needle not be allowed to rotate as it passes through the sealing membrane and allowed to rotate or otherwise act on the eye opening of the eye cap only after full penetration and passage through the sealing membrane in order to prevent coring. It is noted that coring is not as great a concern with small diameter needles or soft sealing membranes.
Several devices, notably U.S. Pat. Nos. 4,710,170 to Haber and 4,592,744 to Jagger must be partially disassembled to be rendered safe. Disassembly is time consuming and confusing for users. Jagger points out in a New England Journal of Medicine article in August 1988, that the risk of injury depends upon the type of device used and that devices requiring disassembly have the highest risk. She investigated 326 needle-stick injuries in over a 10 month period and found that 17% occurred before or during use of the devices and 13% during or after disposal of the devices. Because of shortcomings in structural features, there is still an incentive for the worker to recap the device. The single largest cause of injury is due to recapping. In the Jagger study, workers missed the cap and stuck themselves when attempting to cover a used needle in 17.8% of the injuries. Needles piercing caps during recapping after use accounted for 10.7% while needles protruding from trash accounted for 8.9%. OSHA statistics suggest that over two million workers are at risk in hospitals alone. It is apparent that needle boxes are often not within easy reach. There may be one box on a ward or floor, usually located at the nurse's or aid's station. The distance from where the needle is used and should be disposed can be substantial, making disposal inconvenient. Additionally, the disassembled components are often contaminated, which detracted from the objective of disassembly and encourages recapping of the needle.
One of the primary shortcomings of many existing retracting needles is that each requires use of a non-standard needle support structure. As seen in the Vining patent previously mentioned, this means providing a needle with a base that has to be specially manufactured as opposed to using standard parts. When standard components are utilized, familiarity among users is retained and parts are interchangeable. Lack of familiarity increases the likelihood of misuse and increases the frequency of accidents.
U.S. Pat. Nos. 2,880,725 to Kendall teaches that a needle can be mounted from the inside of a cartridge or glass syringe barrel. This structure, while having features of interest, requires that the barrel opening be modified so as to receive and anchor the needle by a pawl mechanism. With the needle so anchored, it cannot be returned to a retracted position. Protection of the needle point is not possible after needle use. Also, U.S. Pat. No. 4,735,311 to Lowe teaches that insertion of a needle into a cartridge eye cap can be accomplished. However, no provision is given to prevent coring of the cartridge membrane or to lock the needle base into the eye opening of the eye cap.
U.S. Pat. No. 4,781,683 to Wozniak et. al. shows self-annulling syringes that cannot be shared or reused. However, there is no control over exposure of the injectant to the hydraulic expansion plug which is positioned in the outflow channel of the syringe. The instant invention eliminates such a problem by virtue of exposure prevention until the needle is retracted. A filter plug in the plunger piston barrel of the present invention allows a venting mechanism for gas while preventing passage of a liquid. This would be desirable for blood gas analysis as well as syringe pump medication delivery where gas such as CO.sub.2 is produced and should be removed.
U.S. Pat. No. 4,735,311 to Lowe et. al. teaches a needle shield assembly for detachably mounting the shield hub or eye cap of a syringe. The shield is connected by a two step snap fit in which rotation of the shield cannot be prevented and therefore, coring is possible. The needle is unified with the plastic base. In the present invention, the base or cap ferrule of the cap might be independently removed leaving the central cap to protect the needle. Alternately, both parts may be removed together to leave the needle behind and fastened to the eye cap.
Interchangeable parts and molds provide that only slight modifications of existing parts or molds can accomplish the objectives of quality, performance and integrity of a new product structure. Retaining conventionally accepted mechanisms and parts when possible helps minimize training time and device costs and assures easy assimilation into a use environment.
The contributions of this invention are readily applicable to altered cartridges, or pre-manufactured cartridge-needles that are retractable, or a cartridge used to obtain a blood sample, or a cartridge that is manually mounted with a needle prior to syringe loading and allowing access to a fluid therein if so desired.
Two part syringes for the injection of medicaments are well known wherein two sub-assemblies are threadedly connected to one another prior to use of the syringe. Prior art examples include U.S. Pat. Nos. 2,778,359 to Friedman; 4,33,457 to Margulies; and 4,642,103 issued Feb. 10, 1987 to Gettig. In these syringe assemblies, one sub-assembly comprises a plunger rod slidably supporting a head member that is, in turn, provided with either external or internal threads. This threaded member is adapted to engage mating threads formed adjacent to the rear end of the syringe barrel or cartridge.
The present invention includes structure that corrects for the shortcomings of such prior art. Included herewith is an interlocked injector assembly for use with a conventional or retractable glass barrel with standard or modified eye cap. The firm interlock of the two subassemblies is achieved through the interaction of a twin lead threaded connector with opposing detents consisting of bumps, ramps or dimples between threads adapted to slidably surround the glass cartridge barrel and a second connector element housing the slidable plunger rod having two surface, strategically placed, corresponding bump or ramps 180 degrees apart which mate with the bumps between threads of the hub connector. As the bumps slide past each other, a resilient or compressible collet ring as part of the first connector element surrounding the glass barrel of a cartridge is axially compressed and locked into position to firmly secure the two interlocking connector elements and compressing the smooth external surface of the cartridge barrel wall. The same tip mechanism is duplicated in the example of the syringe gun injector assembly as well as the tip protected biopsy needle and breast marking system. This mechanism may also be applied to screw caps and containers generally used in the general packaging industry to assure seal integrity during shipment or during vacation or business travel by providing tactile reassurance of a seal being formed and the cap secured during single or repetitive use.
Pre-mounted cartridge needles have shortcomings whereby it is undesirable to expose the metal in the needle base to some agents prior to use. Rubber or other poorly secured needle caps encourage leakage or possible needle-stick injury when needles penetrate sidewalls. A rod contained in the base of the cap parallel to the sidewalls may alleviate this problem. A rigid cap that is capable of forming an airtight seal with the base of the needle may prevent fluid entry. Such a close fitting cap and cartridge could be loaded in combination into a dental syringe holder. Needles may be encapsulated after use by being made to retract into the glass containment means after use is complete.